An error building Qt libraries for the raspberry pi

Question

I am trying to compile the Qt 5 libraries for my RPI, but it always crashes.

These are the guides I have tried to follow:

http://qt-project.org/wiki/RaspberryPi_Beginners_guide
http://qt-project.org/wiki/RaspberryPi

I have downloaded the cross-compiler and sysroot-image according to the guide and pulled the Qt5 sources from the git repo.

After following one of the guides I am now stuck at make.

This is the error I am receiving:

.obj/release-shared/qlibrary_unix.o: In function `QLibraryPrivate::load_sys()':
qlibrary_unix.cpp:(.text+0xf84): warning: Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libdl.a(dlopen.o): In function `dlopen':
(.text+0xc): undefined reference to `__dlopen'
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libdl.a(dlclose.o): In function `dlclose':
(.text+0x0): undefined reference to `__dlclose'
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libdl.a(dlsym.o): In function `dlsym':
(.text+0xc): undefined reference to `__dlsym'
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libdl.a(dlerror.o): In function `dlerror':
(.text+0x0): undefined reference to `__dlerror'
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libm.a(feholdexcpt.o): In function `feholdexcept':
(.text+0x48): undefined reference to `_dl_hwcap'
/home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libm.a(fesetenv.o): In function `fesetenv':
(.text+0x64): undefined reference to `_dl_hwcap'
collect2: virhe: ld:n paluuarvo oli 1                                           # collect2: error: ld returnvalue was 1
make[2]: *** [../../lib/libQt5Core.so.5.0.0] Virhe 1                            # Error 1
make[2]: Poistutaan hakemistosta "/home/esa/qtonpi/qt5/qtbase/src/corelib"      # Leaving directory
make[1]: *** [sub-corelib-make_first] Virhe 2                                   # Error 2
make[1]: Poistutaan hakemistosta "/home/esa/qtonpi/qt5/qtbase/src"              # Leaving directory
make: *** [sub-src-make_first] Virhe 2                                          # Error 2

Answer 1

Fix the paths of the libraries in your sysroot. Some libraries are symlinks to absolute paths which are broken when placed in your system. Check something like /home/esa/qtonpi/rpi_image/usr/lib/arm-linux-gnueabihf/libdl.so or similar. You should see those are broken symlinks to absolute paths. Fix all of those. In the documents you reported a script for this purpose is provided. Did you run it (https://gitorious.org/cross-compile-tools/cross-compile-tools/blobs/master/fixQualifiedLibraryPaths)?

Try also to check this if you still encounter troubles: I wrote down some notes compiling a recent version from the git for the wheezy image.

Answer 2

An answer for those who tried both the existing answers and they didn't work:

It might happen that the Raspbian image you downloaded doesn't contain symlinks for libdl and libdm in the /usr/lib/ folder.

In that case the fixQualifiedLibraryPaths won't help you as it can't find the symlinks. Copying libdl.so and libm.so might also fail, for example, if you use a flash drive to copy data from your existing Raspberry Pi, it won't copy them as symlinks, but will copy the libraries themselves. However, for the build to succeed, it seems to require symlinks.

I looked at what libdl and libdm in the /usr/lib/ folder of my Raspberry Pi point at

cd /usr/lib/arm-linux-gnueabihf/
ls -l libld.so libm.so

Do the same for the found files until they are no longer symlinks but normal files.

On my system it turned out they are called libdl-2.13.so and libm-2.13.so and reside in /lib/arm-linux-gnueabihf/ instead of /usr/lib/...

Going back to my PC, I found these exact files in the /lib/arm-linux-gnueabihf/ folder (if you don't find them, you can copy them from your Raspberry Pi). So I created symlinks for them in the /usr/lib/arm-linux-gnueabihf/ folder :

sudo ln -s /lib/arm-linux-gnueabihf/libdl-2.13.so /usr/lib/arm-linux-gnueabihf/libdl.so
sudo ln -s /lib/arm-linux-gnueabihf/libm-2.13.so /usr/lib/arm-linux-gnueabihf/libm.so

After this, qtbase was compiled successfully.

(note, that in order to continue to cross-compile from Qt, you have to keep the image of your SD card mounted on your PC (as described in the guide), but that's not enough: you have to mount it before starting Qt Creator)